Children don’t want to break off their relationship with their parents, whether that child is twenty-five or sixty-five. The Still Face Experiment by Dr Edward Tronick in 1975 showed babies will attempt to fix a bond with their caregiver.
"An infant, after three minutes of 'interaction' with a non-responsive expressionless mother, rapidly sobers and grows wary. He makes repeated attempts to get the interaction into its usual reciprocal pattern. When these attempts fail, the infant withdraws [and] orients his face and body away from his mother with a withdrawn, hopeless facial expression." — Edward Tronick
When the mother goes back to being attentive and expressive, the infant is overjoyed. This experiment shows our need for connection with our parents starts very early in life. Much like the infants in this experiment, as a grown-up child I would feel overjoyed if my parents apologised and proved they had changed.
Maybe these children leave their parents because they are brave, not because they are ungrateful brats. Maybe they gave their parents plenty of chances to repair their bond.